The present invention relates to 5-alkoxy-1,2,4-triazolo[4,3-c]pyrimidine-3(2H)-thione compounds and to their use in the preparation of 5-alkoxy[1,2,4]-triazolo[1,5-c]pyrimidine-2(3H)-thione compounds and 3-hydrocarbylthio-5-alkoxy-1,2,4-triazolo[4,3-c]pyrimidine compounds. It further relates to the use of 3-hydrocarbylthio-5-alkoxy-1,2,4-triazolo[4,3-c]pyrimidine compounds for the preparation of 2-hydrocarbylthio-5-alkoxy[1,2,4]triazolo[1,5-c]pyrimidine compounds.
5-Alkoxy[1,2,4]triazolo[1,5-c]pyrimidine-2-sulfonamide compounds that are potent herbicides are described in U.S. Pat. No. 5,163,995 and are disclosed to be prepared in a multistep process that utilizes appropriately substituted 2-hydrocarbylthio-5-alkylthio-1,2,4-triazolo[4,3-c]pyrimidine compounds as intermediates. The preparation requires a substitution reaction wherein the alkylthio moiety is replaced with an alkoxy moiety in the presence of an ethylenically unsubstituted compound capable of reacting with and removing the displaced alkanethiol. This process is lengthy, produces the desired products in only moderate yield, and results in a alkylthioethyl moiety-containing compound by-product which must be disposed of as waste. Improved methods of preparing herbicidal 5-alkoxy[1,2,4]triazolo[1,5-c]pyrimidine-2-sulfonamide compounds, including improved methods for preparing intermediates that are useful in their preparation, would be of considerable value as would the intermediates that would be required to implement the improved methods.
Neither 5-alkoxy-1,2,4-triazolo[4,3-c]pyrimidine-3(2H)-thione compounds nor 5-alkoxy[1,2,4]triazolo[1,5-c]pyrimidine-2(3H)-thione compounds have been described in the art. 3-Hydrocarbylthio-5-alkoxy-1,2,4-triazolo[4,3-c]pyrimidine compounds are also novel.